Merge branch 'fix-v2-chat-unknown-event-incomplete' into 'master'

Fix incomplete unknown event stream from V2 Chat Agent

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/166424



Merged-by: Mark Chao <mchao@gitlab.com>
Approved-by: Tetiana Chupryna <tchupryna@gitlab.com>
Approved-by: Mark Chao <mchao@gitlab.com>
Co-authored-by: Shinya Maeda <shinya@gitlab.com>